fix: remove UploadBatcher crash window, make bot concurrency configurable, fix all test import paths

- Removed UploadBatcher (src/infrastructure/telegram/upload-batcher.ts + DI):
  pending uploads no longer lost on crash, files sent directly to Telegram
- Changed upload-controller to use Bun.file().stream() instead of createReadStream
- Made PER_BOT_CONCURRENCY configurable via TELEGRAM_BOT_CONCURRENCY env
- Fixed 18 test files with updated import paths and mock shapes
- Updated package.json test script: telegramQueue.test.ts → bot-pool.test.ts
- Build, lint, and test suite all pass

test/bot.test.ts

@@ -1,6 +1,6 @@
 import { afterAll, beforeEach, describe, expect, it, mock, spyOn } from 'bun:test';
+import logger from '../src/shared/logger/index';
 import type { TelegramMediaMessage } from '../src/shared/utils/file';
-import logger from '../src/utils/logger';
 
 // Mock environment
 process.env.BOT_TOKEN = process.env.BOT_TOKEN || '123456789:ABCdefGhIJKlmNoPQRsTUVwxyZ';